Vehicle systems may include an engine with an exhaust gas treatment system coupled in its exhaust passage in order to control regulated emissions. In some examples, the exhaust gas treatment system may include a selective catalytic reduction (SCR) system in which an exhaust fluid or reductant, such as urea or ammonia, is added to the exhaust stream upstream of a catalyst such that NOx may be reduced by the catalyst. In such an example, the exhaust fluid may be held in an exhaust fluid storage tank. The level of exhaust fluid in the exhaust fluid storage tank may be monitored, such as via a dedicated sensor or based on a vehicle distance travelled since a last refill. Accordingly, the exhaust fluid storage tank may be periodically refilled.
One approach for exhaust fluid management is shown by Huang et al. in US 20080306631. Therein, when the exhaust fluid level in the storage tank reaches a lower limit, a distance travelable at the normal rate of exhaust fluid consumption is estimated. If the controller determines that a refill station is not available within the estimated distance, exhaust fluid dosing is adjusted to allow for more conservative use of the fluid.
However the inventors herein have identified potential issues with such an approach. As an example, due to limited availability of urea, there may be situations where the vehicle cannot reach a urea filling station before the storage tank is empty. When traveling in remote areas where area is not available within long distances, the customer may even need to carry a spare bottle of urea. As such, this may be messy and inconvenient. As another example, currently available urea sensors may not be highly sensitive or consistent. As a result, the information regarding reductant usage, range of urea availability in the tank, and internal volume may be incomplete. In addition, since the usage range for the urea fluid is not proportional to the storage tank, there may be confusion caused to the customer. Further confusion may be caused to the operator due the higher frequency with which the fuel tank needs to be refilled as compared to the exhaust fluid storage tank. Further still, due to the less frequent need for urea refilling, many refilling stations may only be configured to store fuel, and not urea. Consequently, even when a vehicle operator reaches a refilling station, urea may not be available for refilling. Overall, there may be situations where the exhaust fluid tank goes empty, degrading engine performance.
The inventors have recognized that at least some of the above issues may be addressed by a method for a vehicle system comprising: in response to a fluid level in each of an exhaust fluid tank and a fuel tank, providing a vehicle operator with one or more alternate driving route suggestions, the suggested driving route(s) including a refilling station. In this way, urea tank refilling may be synchronized with fuel tank refueling to better ensure that a vehicle is not operated with an empty urea tank.
As an example, a vehicle may be configured with a fuel tank for storing diesel fuel and an exhaust fluid storage tank for storing urea reductant. While the vehicle is travelling on a route to a defined destination, the controller may determine a rate of usage of each of the fuel and reductant based on operating conditions as well the planned route. The controller may further monitor a fluid level of the fuel tank and the exhaust fluid storage tank. Based on the predicted usage over the planned route, and the level of fluid in each tank relative to respective lower limits, the controller may determine if fuel and/or reductant refilling is required before the vehicle reaches the destination. If refilling of either tank is required, the controller may suggest one or more alternate driving routes to the destination via refilling stations where the required fluids are available. For example, a first alternate route via a first refilling station where at least diesel fuel is available may be suggested if the fuel tank is expected to reach the lower limit before the urea tank. If the urea tank is expected to reach the lower limit before the fuel tank, a second alternate route via a second, different refilling station where at least urea is available may be suggested. Further still, if each of the urea and diesel tank are expected to reach their lower limit, a third alternate route via a third refilling station where both diesel and urea are available may be suggested. The different routes may be selected based on the differential rate of fuel usage relative to reductant usage. In particular, the routes may adjust for the fact that fuel usage may require more frequent fuel tank refilling while reductant usage may require less frequent urea tank refilling. For example, the urea tank may need to be refilled once for every 3-4 times the fuel tank is refilled. The controller may use preferences stored in a user's profile to select routes and refilling stations. For example, the selections provided may be based on a user's preference for fuel price, urea price, fuel brand or dealer, urea brand or dealer, type of refilling facility available (bottle or pump) etc. Furthermore, the routing suggestions may be dynamically updated based on changes to fuel and urea as driving patterns and conditions change.
In this way, reductant refilling can be ensured and vehicle operation on an empty reductant tank can be pre-empted. By continually monitoring urea usage and updating a vehicle operator about urea levels and urea range, the operator may be influenced to drive more conservatively when urea levels are low. By synchronizing urea refilling and fuel tank refilling with navigational inputs to refilling stations selected on the fuel and urea ranges, refilling efficiency is improved. By enabling operators to share refilling details, such as via a social media community or hub, urea refilling information can be retrieved with less time wastage. In addition, fleet managers can have better control of their vehicles remotely and can allocate each one more efficiently depending on the fuel/exhaust fluid remaining for a specific job.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.